Canon RF 100mm F2.8 L Macro IS USM

Testers found it very sharp across the frame from f/2.8, peaking around f/4 to f/5.6 and still very fine at f/11. Distortion is negligible and lateral CA is low, but raw vignetting is high at f/2.8 (about 2 stops) and needs correction or stopping down. Background blur is smooth and highlights are clean in the centre, while foreground blur is harsher and corner highlights turn to cat's eyes wide open.

Autofocus is fast and quiet for a macro lens, and the IS is effective, though testers did not see the full 8-stop claim. The SA ring splits opinion. Some value it for painterly bokeh and video, others call it a gimmick, and it softens the in-focus area as well as the blur. One lab test found the focus point moving back as the aperture closes at close range. Focus breathing results conflict between tests. The price is well above the EF 100mm L, and it is a long lens for a 100mm.

An owner shooting flowers and birds reports autofocus fast enough to track wind-blown flowers handheld in Servo mode, and even birds in flight at close range. He finds it sharp to the corners from f/2.8 to f/16 with a smooth transition into the out-of-focus areas, and in his own careful tests at 1x and 1.4x he saw no focus shift.

He measured about 3.5 stops of handheld benefit from the stabiliser, well short of Canon's figure but still useful. He keeps the SA ring locked and the control ring disabled to avoid accidental changes. His reservations are some flare with the sun on the front element (not an issue with the hood fitted) and vignetting at f/2.8.